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my filtration should be more than sufficient. i have dual aqua-tech 30-60 filters (330gph each). and as long as i keep the same media in them i should be fine as far as not recycling i hope.

also, it says here in the original post to drain the water down to 6 or 8 inches. what exactly is the best method to get all the rocks out? i mean short of taking 100% of the water out and just lifting the tank and drumping it into a trash can it seems like any other method is going to take a long time to ensure getting it all. i could drop a vaccum extension in there but not if it's under water...

As far as getting the rocks out, you certainly don't want to tip your tank over and dump it. That is a great way to crack your glass or scratch the hell out of your acrylic. Either way = bad.

How you go about removing the substrate you have now is up to you, but you definitely want to leave a little water in the tank while you do it.

leaving as much as possible is best right?

and oh yeah, forgot to ask a very important question. i thought i had read somewhere (can't remember where) that using sand in a tank that is acrylic is a disaster waiting to happen... seems like it said something about the sand creates fine scratches that can ruin the tank. does that sound right? i have no idea if my tank is acrylic or not. this is probably a stupid question. maybe they are all acrylic? i have no idea. that's why i'm glad you guys know your stuff and can help me! it's much appreciated.

Glass tanks are more common place if you got it from a big box store.
Sand can scratch, but its still used.

Not sure I understand what you are referring to when you say "leave as much in as possible". If you're talking about water, its not a big deal, you just want to have some water to diffuse any substrate that gets dropped and for friction reduction.

Glass tanks are more common place if you got it from a big box store.
Sand can scratch, but its still used.

Not sure I understand what you are referring to when you say "leave as much in as possible". If you're talking about water, its not a big deal, you just want to have some water to diffuse any substrate that gets dropped and for friction reduction.

Changing substrate can be a bit laborious, but not difficult process.

it came from petsmart. either way it sounds like it's something i should avoid putting sand in if that's what i want.

i meant leaving in as much water as possible because that would be that much more water that is already closer to the right temperature and that the fish have been in.

If it came from petsmart, you can be fairly assured its an All-Glass Aquarium's tank.

I must have missed it- if you're changing substrate out in a tank that already has fish, then yes, you need to leave them in as much water as possible, or preferably, move them to a separate tank.

And to clarify an earlier statement, sand can scratch acrylic, but acrylic owners still use it. Sand won't scratch glass under the conditions you're attempting.

yeah my tank has 16 fish at the moment.

i hadn't thought about this until just now, but i actually could borrow my friends tank that he uses to hosue his fish when he cleans his tank. it's only 10 gallons, but surely it would be ok for a couple hours time. and it has a hood/light/filter... everything. i could empty out 10 gallons of water from my tank and put it in his tank with all the fish.

cleaning the sand concerns me since i don't know what i'm doing. i can't really start cleaning it until bucket by bucket i am able to put what's been cleaned into the tank, meaning the old gravel substrate has to be removed. and i can't add any cleaned sand into the tank with the fish in there. i'm afraid they might be out of the tank for a long while, but at least this way they would be in the exact same water with filtration.

In this situation you could get one of those big storage containers and dump the cleaned sand into that until it is all rinsed very well and ready to be put in the tank. It does need to be rinsed extremely well especially if you want to put your fish right back in the tank. So small amounts in a bucket until the sand is stirred and everything settles within about a minute. Also stir dechlorinated water into the sand before adding to the tank so you wont kill your bacteria with chlorine that will be in the sand. By putting the sand in a storage container you can be sure that you have rinsed it all well and have not rushed.